Deaf persons communicate effectively with each other by means of manual signs. What is the place of signs in the internal cognitive operations of the deaf? The general approach taken to this question is to compare the functions of signs for the deaf with those of speech for the hearing. Two methods of investigation are proposed to tackle this question. One is designed to test to what extent deaf subjects represent information internally through the medium of signs. For this purpose deaf children in the age range of 8-12 years will be shown a series so arranged that some later signs will be similar to preceding signs either in meaning or in physical form. Their task will be to indicate for each sign whether it appeared before in the sequence (Yes) or not. The number of "Yes" responses to new signs which are related to preceding signs will serve as an index of the form of internal coding. The second method involves testing whether the signs of the deaf are processed more efficiently in the left cerebral hemisphere, which is dominant for speech and language, than in the right hemisphere. This will be examined by projecting visual outlines of signs to deaf individuals and asking them to indicate by pressing a Yes or No button, connected to a timing device, whether the outline corresponds to a picture of the sign they had just seen. The projections will be for very short durations to the left or right visual fields of the eyes. The latency of the subjects' responses will serve as an indicator as to which of the two hemispheres specializes in the analysis of signs.